Les ferments lactiques, d’une importance industrielle considérable, sont très largement commercialisés sous forme concentrée, congelée ou lyophilisée en vue de leur utilisation ultérieure dans les procédés industriels tels que les procédés de production de fromage. Cependant, les procédés de stabilisation (congélation et lyophilisation) engendrent différents stress qui peuvent conduire à de faibles taux de survie et des pertes de fonctionnalités des microorganismes. Dans ce contexte, ce travail de thèse vise à mieux comprendre l’incidence de l’état physiologique des cellules de L. lactis TOMSC161 au moment de la récolte sur leur tolérance à la lyophilisation et au stockage, et de développer des outils simples mais efficaces d’évaluation de l’état physiologique des cellules au cours de la fermentation pour les industriels. Dans une première partie, l’influence de différents paramètres de fermentation (température, pH et phase de croissance) sur la croissance et la résistance de L. lactis TOMSC161 à chaque étape du procédé de lyophilisation et au stockage a été étudiée. Alors que les performances de la souche ne sont pas dégradées après congélation, L. lactis s’est avéré sensible au séchage et au stockage à température ambiante. De plus, la température de fermentation et l’instant de récolte influencent la résistance au séchage de cette bactérie. Ainsi, les cellules de L. lactis TOMSC161 cultivées à 32 °C, pH 6,2 et récoltées tardivement (en phase stationnaire avancée) présentent une croissance optimale et la meilleure résistance à la lyophilisation et au stockage à 4 °C. Dans une seconde partie, une caractérisation approfondie de la membrane de L. lactis TOMSC161 aux niveaux biochimique et biophysique a été réalisée au cours de fermentations à différentes températures (22 et 30 °C) et a été mise en lien avec la résistance des ferments à la lyophilisation et au stockage. La cyclopropanation des acides gras insaturés de L. lactis TOMSC161 au cours de la fermentation est reliée à une rigidification de la membrane et permet d’améliorer la tolérance des cellules à la lyophilisation et au stockage. A l’inverse, la culture des cellules à une température inférieure à la température optimale de croissance induit une adaptation homéovisqueuse de la membrane, mise en évidence par la température de transition lipidique, mais n’a pas induite une amélioration de la résistance à ce procédé de préservation. Dans une troisième partie, la caractérisation de l’état physiologique des cellules de L. lactis TOMSC161 a été complétée au niveau du transcriptome, du protéome et de l’état d’oxydation cellulaire. Le procédé de lyophilisation provoque la formation d’espèces réactives de l’oxygène (ROS) intracellulaires qui dégradent la performance des ferments au cours du stockage. Par ailleurs, l’état d’oxydation des cellules diminue au cours de la fermentation et est expliqué, en phase stationnaire, par un ralentissement du métabolisme énergétique aérobie et une induction des réponses au stress oxydatif. Cette « pré-adaptation » initiale des cellules de L. lactis TOMSC161 au cours de la fermentation permet, là encore, une amélioration de leur tolérance à la lyophilisation et au stockage par une limitation de l’accumulation de ROS lors de ce procédé de préservation. Ce travail se conclut par une vérification des fonctionnalités du ferment lyophilisé, dans les conditions de production optimisées lors de cette thèse, en fabrication fromagère. Malgré l’étape de lyophilisation, les propriétés technologiques de L. lactis TOMSC161 sont conservées, validant ainsi le travail d’optimisation réalisé. / Lactic acid bacteria, which have a significant industrial importance, are widely distributed in frozen or freeze-dried state for further use in industrial processes such as cheesemaking. However, stabilization processes (freezing or freeze-drying) causes different stresses which can lead to low survival rates and functionality losses of microorganisms. In this context, this thesis aimed at better understanding the impact of the physiological state of L. lactis TOMSC161 cells during fermentation on their freeze-drying and storage resistance, and at developing simple but efficient tools to evaluate the cells physiological state during fermentation for industrials.In the first part of this work, the influence of fermentation parameters (temperature, pH and harvesting time) on the growth and resistance of L. lactis TOMSC161 to each step of the freeze-drying process and storage has been investigated While the strain performance was not deteriorated after freezing, L. lactis was sensitive to the drying step and to ambient temperature storage. Moreover, the fermentation temperature and the harvesting time influenced the drying resistance of this bacterium. L. lactis TOMSC161 cells grown at 32 °C, pH 6.2 and harvested late (at late stationary phase) exhibited therefore both an optimal growth and the highest resistance to freeze-drying and storage at 4 °C. In the second part, a deep characterization of the L. lactis TOMSC161 membrane at a biochemical and biophysical level was analyzed during fermentation at different temperatures and was linked to the freeze-drying and storage resistance of starters. The cyclopropanation of unsaturated fatty acids of L. lactis TOMSC161 during fermentation was correlated with a membrane rigidification and allowed an improvement of the cell tolerance to freeze-drying and storage. Conversely, cultivating cells at lower fermentation temperature than the optimum growth temperature induced as expected a homeoviscous adaptation as evidenced by lowered lipid phase transition temperature but did not induce any improvement of resistance to this preservation process.In the third part, the physiological state characterization of L. lactis TOMSC161 cells was completed by investigating at the transcriptomic and proteomic levels as well as the cellular oxidation state. The results proved that the freeze-drying process caused intracellular reactive oxygen species (ROS) formation, responsible of degradation of the starter performance during storage at 25 °C. Furthermore, the cellular oxidation state decreased during fermentation and was explained, in the stationary phase, by a slowdown of the aerobic energy metabolism and the induction of oxidative stress responses. This initial “pre-adaptation” of L. lactis TOMSC161 during fermentation allowed improving their tolerance to freeze-drying and storage by a limitation of ROS accumulation through the whole preservation process.Finally, this work has been concluded by verifying the functionalities of starter freeze-dried in the optimized production conditions defined in this thesis during cheesemaking. Despite the freezedrying step, the technological properties of L. lactis TOMSC161 were preserved, thus validating the performed optimization.

Detta examensarbete omfattar produktutvecklingen av en komponent till en mätutrustning som ska mäta flytbarheten hos smält metall. Arbetet har utförts hos Bryne AB och har lett fram till koncept-, material- och tillverkningsförslag för komponenten. Arbetet har även utvärderat ett för gjuteribranschen nytt formmaterial som alternativ till dagens gjutsand. Tester har gjorts för att se om återvunnet (material x) går att använda som formmaterial till högtemperaturapplikationer. / This thesis covers the product development of a component for a measuring device that measures the fluidity of molted metal. The work has been performed at Bryne AB and has led to concept, material and manufacturing proposal for the component. This work has also evaluated new molding material to be used in foundries that can be an alternative to today's molding sand. Tests have been made to see if recycled (material x) can be used as mold material for high temperature applications. / <p>Uppladdad version av rapporten är en offentlig kopia av orginalrapporten. I den offentliga versionen har känslig information fått ett annat namn för att inte påverka uppdragsgivarens patentansökan.</p>

Submitted by BRUNO HENRIQUE PINTO (engbhpin@gmail.com) on 2018-06-29T13:15:23Z No. of bitstreams: 1 Execução de blocos para alvenaria estrutural utilizando concreto fluido 2018 (2).pdf: 4983067 bytes, checksum: cca8dd5aade17e86646b1fd28326a3f9 (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-06-29T14:16:19Z (GMT) No. of bitstreams: 1 pinto_bh_me_ilha.pdf: 4983067 bytes, checksum: cca8dd5aade17e86646b1fd28326a3f9 (MD5) / Made available in DSpace on 2018-06-29T14:16:19Z (GMT). No. of bitstreams: 1 pinto_bh_me_ilha.pdf: 4983067 bytes, checksum: cca8dd5aade17e86646b1fd28326a3f9 (MD5) Previous issue date: 2018-06-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As complicações ocasionadas pelas irregularidades presentes na face de assentamento dos blocos de alvenaria estrutural, provenientes de procedimentos correntes de fabricação, possibilita um campo de estudo para otimização na melhoria dessas irregularidades. Para tanto, este trabalho tem por finalidade propor uma alternativa de fabricação dos blocos de alvenaria estrutural através do uso e aplicação de concreto fluido com os traços 1:3, 1:5 e 1:7, cujas resistências à compressão deles e dos prismas, atendam às exigências das normas NBR 15961-1 e NBR 15961-2. Assim, além de moldados e confeccionados os blocos e os prismas, neste trabalho são apresentados ensaios de ambos, bem como os ensaios das argamassas de assentamento mista e polimérica. Em alguns destes ensaios utilizaram-se LVDTs e Strain-Gages, com objetivo de verificar os seus deslocamentos e suas deformações, e consequentemente as tensões atuantes, nos blocos e nos prismas. / Complications arising from imperfections on the bonded surface of structural masonry blocks, from current manufacturing procedures, makes it a field of study for optimization in the improvement of these irregularities. To this end, this paper aims to propose an alternative to the manufacture of structural masonry block through the use and application of fluid concrete with mixture 1:3, 1:5 and 1:7, whose resistance to compression them and prisms, meet the requirements established by the Brazilian technical standards NBR 15961-1 and NBR 15961-2. Thus, this work describes tests performed on blocks and prisms. The prisms were tested with mixed and polymeric block-laying mortars. In some of these tests using LVDTs and Strain Gages to check their displacements and their deformations, and consequently tensions, in the blocks and prisms.

Orientador: Maria da Consolação Fonseca Albuquerque / Resumo: As complicações ocasionadas pelas irregularidades presentes na face de assentamento dos blocos de alvenaria estrutural, provenientes de procedimentos correntes de fabricação, possibilita um campo de estudo para otimização na melhoria dessas irregularidades. Para tanto, este trabalho tem por finalidade propor uma alternativa de fabricação dos blocos de alvenaria estrutural através do uso e aplicação de concreto fluido com os traços 1:3, 1:5 e 1:7, cujas resistências à compressão deles e dos prismas, atendam às exigências das normas NBR 15961-1 e NBR 15961-2. Assim, além de moldados e confeccionados os blocos e os prismas, neste trabalho são apresentados ensaios de ambos, bem como os ensaios das argamassas de assentamento mista e polimérica. Em alguns destes ensaios utilizaram-se LVDTs e Strain-Gages, com objetivo de verificar os seus deslocamentos e suas deformações, e consequentemente as tensões atuantes, nos blocos e nos prismas. / Abstract: Complications arising from imperfections on the bonded surface of structural masonry blocks, from current manufacturing procedures, makes it a field of study for optimization in the improvement of these irregularities. To this end, this paper aims to propose an alternative to the manufacture of structural masonry block through the use and application of fluid concrete with mixture 1:3, 1:5 and 1:7, whose resistance to compression them and prisms, meet the requirements established by the Brazilian technical standards NBR 15961-1 and NBR 15961-2. Thus, this work describes tests performed on blocks and prisms. The prisms were tested with mixed and polymeric block-laying mortars. In some of these tests using LVDTs and Strain Gages to check their displacements and their deformations, and consequently tensions, in the blocks and prisms. / Mestre

Made available in DSpace on 2015-03-13T17:10:58Z (GMT). No. of bitstreams: 1 MaxsuelMM_DISSERT.pdf: 4624416 bytes, checksum: 0490a56bd282fc3dc15d7c3612fc0ede (MD5) Previous issue date: 2014-03-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The state is responsible for creating regulatory and infrastructural conditions in a determined territory. These actions generate macrodynamics, however, in some cases they show selective and restricted, as in the case concerning the transportation sector. The actions of the Brazilian government aimed at territorial fluidity nowadays are evidenced especially by the Growth Acceleration Program (PAC). The PAC in the axes allocated to the transport sector, called logistics, which in turn appears as a pressing necessity and as an ideology of the current period. Therefore, within this context of territorial transformations resulting from this program we situate our work that aims to understand how the actions of the State implemented and planned under the PAC are configuring or can configure the brazilian territorial logistics, particularly in the state of Rio Grande do Norte / O Estado ? respons?vel por criar condi??es normativas e infraestruturais em um determinado territ?rio. Essas a??es geram macrodin?micas, contudo, em alguns casos elas se mostram seletivas e restritas, como no caso das concernentes ao setor de transporte. As a??es do Estado brasileiro destinadas a fluidez territorial na atualidade s?o consubstanciadas, especialmente, pelo Programa de Acelera??o do Crescimento (PAC). O PAC nos eixos destinados ao setor de transporte ? batizado de log?stica, que por sua vez, se apresenta como uma necessidade premente e como uma ideologia do atual per?odo. Portanto, dentro desse contexto de transforma??es territoriais advindas com esse programa situamos nosso trabalho, que objetiva compreender como as a??es do Estado concretizadas e planejadas no ?mbito do PAC est?o configurando ou podem configurar a log?stica territorial brasileira, particularmente, a do estado do Rio Grande do Norte

A Doença de Alzheimer (DA) é uma desordem neurodegenerativa progressiva que causa comprometimento cognitivo em idosos. O diagnóstico clínico da DA é complexo. Existe uma grande necessidade de técnicas capazes de detectar a doença nos estágios iniciais, tanto para auxiliar o diagnóstico quanto para monitorar a efetividade dos tratamentos disponíveis. As alterações bioquímicas da DA são resultado de processos celulares como o metabolismo da proteína precursora do amilóide (APP), fosforilação da tau, stress oxidativo, inflamação e desregulação lipídica. Até o momento não existem marcadores bioquímicos para auxiliar o diagnóstico da DA. Este trabalho avaliou três possíveis candidatos a marcadores bioquímicos para a DA. Foram investigados a razão da APP (rAPP) de 130/110 kDa, fluidez de membrana e atividade da fosfolipase A2 em plaquetas de pacientes com DA e Comprometimento Cognitivo Leve (CCL), comparando-se seus resultados com controles idosos saudáveis. A fluidez das membranas das plaquetas foi avaliada por meio da anisotropia com a sonda fluorescente DPH (Difenilhexatrieno); a comparação das razões da APP foi realizada por Western Blotting empregando o anticorpo 22C11 e a da atividade da PLA2 foi determinada por ensaio radioenzimático com substratos e concentrações de cálcio específicas para cada um dos três principais grupos da enzima. A rAPP, as atividades da sPLA2 e iPLA2 estavam significantemente reduzidas na DA quando comparadas com controles, enquanto que a cPLA2 e a fluidez de membrana não apresentaram diferenças entre os grupos. A rAPP e a iPLA2 também apresentaram diferenças significativas entre CCL e DA, além de estarem correlacionadas com os parâmetros cognitivos MEEM e CAMCOG. A rAPP também estava correlacionada com a anistropia do DPH. / Alzheimer disease (AD) is a progressive neurodegenerative disorder that causes cognitive impairment in the elderly. The clinical diagnosis of AD is complex. Thus, there is a great need for sensitive techniques to detect neurodegeneration in the early stages to asset in the diagnosis and to follow the effectiveness of therapy. The biochemical alterations in the AD brain result from cellular processes such as amyloid precursor protein (APP) metabolism, tau phosphorylation, oxidative stress, inflammation and lipid dysregulation. So far there are no biochemical markers to help the AD diagnosis. The purpose of this study was to evaluate three possible candidates to biochemical marker of AD. The APP 130/110 kDa ratio, membrane fluidity and phospholipase A2 activity in platelets of patients with AD and mild cognitive impairment (MCI) were investigated compared to their results with healthy elderly controls. The membrane fluidity of platelets was assessed by the fluorescence anisotropy of DPH (diphenyl-hexatriene); the levels of APP isoforms were evaluated by Western Blot analysis using 22C11 antibody and the PLA2 activity was measured by radio-enzymatic assay with enzyme specific substrate and calcium concentrations for each one of the three main groups of the enzyme. The APP ratio (APPr), the sPLA2 and iPLA2 activity were markedly decreased in AD in comparing with controls, whereas a cPLA2 and membrane fluidity didn\'t show any alteration between the groups evaluated. The APPr and iPLA2 also showed significant differences between MCI e AD, and were correlated with cognitive parameters MMSE and CAMCOG. The APPr was also correlated with DPH anisotropy.

L'objectif principal de notre étude a été la mise au point des formulations liposomiales encapsulant des monoterpènes (MT) et phénylpropènes (PP). Le manuscrit contient deux axes principaux. Le premier a porté sur l'interaction de l'HP-ß-CD, de MT et PP avec des membranes lipidiques. L'HP-ß-CD interagit avec les têtes polaires et les chaînes acyles des phospholipides et montre un effet fluidifiant sur les liposomes formés de DPPC et de Lipoid S100. De plus, l'HP-ß-CD présent dans le compartiment aqueux des liposomes les protège durant la lyophilisation. Les MT et PP interagissent avec la tête et les chaînes alkyles de DPPC entrainant sa fluidification. D'autre part, les composés les plus hydrophobes de la série, ont été plus actifs contre E. coli. Le deuxième axe a été orienté vers la préparation des liposomes conventionnels et du système mixte CD/liposome (ACL). La technique de double encapsulation (ACL2) a été appliquée. Les préparations sont faites à partir de Phospholipon 90H ou Lipoid S100 par la méthode d'injection éthanolique. Les vésicules ont été caractérisées pour la taille, pdI, le potentiel zêta, la morphologie, le rendement et la cinétique de libération de la molécule. L'anéthol (Ane) est utilisé comme un système modèle. ACL et ACL2 ont permis d'améliorer le rendement d'encapsulation de l'Ane et de ralentir sa libération. Les liposomes composés de Lipoid S100 ont montré une meilleure photostabilité et rendement d'encapsulation. Le Lipoid S100 a été ainsi utilisé pour la préparation à grande échelle. Les vésicules obtenues à petite et grande échelle, ont présenté les caractéristiques proches ce qui témoigne d'une bonne reproductibilité de ces procédés / The main objective of this work was the development of liposomal formulations encapsulating monoterpenes (MT) and phenylpropene (PP). The manuscript contains two main axes: the first axis was oriented to the interaction of HP-ß-CD, MTs and PPs with lipid membranes. The HP-ß-CD interacts with the polar heads and acyl chains of phospholipids and showed a fluidizing effect on liposomes formed with DPPC or Lipoid S100. In addition, the incorporation of HP-ß-CD in the internal aqueous compartment of the liposomes protected them during lyophilization. The studied monoterpenes interact with the choline head group and the alkyl chains of DPPC membrane raising the bilayer’s fluidity. In addition, the most hydrophobic compounds of the series, were more active against E. coli. The second axis was oriented towards the preparation of conventional liposomes and drug-in-cyclodextrin-in-liposomes (ACL). The double loaded technique (double loaded liposomes, ACL2) was applied. Phospholipon 90H or Lipoid S100 were used to prepare liposomes by the ethanol injection method. Vesicles were characterized in terms of size, pdI, zeta potential, morphology, loading rate and drug release kinetics. Anethole (Ane) is used as a model system. Compared to conventional liposomes, ACL and ACL2 improve the loading rate of Ane and reduce Ane release. Liposomes prepared with Lipoid S100 showed the best photostability and loading rate. Lipoid S100 is used to prepare liposomes at large scale by membrane contactor and by pilot scale. The characteristics of the vesicles obtained at laboratory and large scale confirmed the reproducibility of the two methods of preparation

C-paper Abstract Title: Fluidity and Solidity in Marilynne Robinson’s Housekeeping Author: Linda Lindqvist The purpose of this essay is to show that fluidity and solidity constitute a central tension on all levels in Housekeeping, and how this tension leads to a choice of either a fluid or a solid lifestyle and view of the world. I focus on fluidity and solidity in gender roles, in memories, in dreams, in nature, and in different perceptions of reality. By taking a closer look at Ruth’s first-person narration (seeing fluidity as not resisting deformation, while solidity resists deformation), we find that the characters in Housekeeping have fluid and solid traits, but that there is no reality that allows mixed manifestations of these. This results in repression of either fluidity or solidity, which creates tension and feelings of loss. Ruth chooses a fluid lifestyle, thus her memories and dreams become mixed with her present, and this also leads her to become a transient, outside gender roles and traditional small town society. Transience in this novel questions all distinctions conventionally made between dream and reality; male and female. In conclusion, this essay highlights how tension between fluidity and solidity is generated on all levels in Housekeeping, and how this leads to either fluid or solid lifestyles since the characters follow a cultural code that dictates a choice between them.

Les fluides complexes tels que les gels, les pâtes ou les émulsions présentent une large gamme d'applications, tant dans la vie quotidienne que dans l'industrie. Parmi ces fluides, les fluides dits ”à seuil” se comportent soit comme des solides élastiques, soit comme des fluides nonnewtoniens selon la contrainte qu'on leur applique. Ces propriétés sont décrites par des lois phénoménologiques (telle que la loi d'Herschel Bulkley), bien que leurs origines soient encore mal comprises. Dans cette thèse, nous nous intéressons à la question des petites échelles, où la structure et les phénomènes interfaciaux jouent des rôles prépondérants dans les écoulements. Ce travail expérimental a été essentiellement mené sur du carbopol, un microgel de polymères et un fluide à seuil modèle. L'étude se concentre essentiellement sur trois points : – La caractérisation rhéologique et structurale des échantillons. L'accent est porté sur l'influence du protocole de préparation sur les propriétés des gels.– Le cas des écoulements confinés de fluides complexes. Ce travail met en évidence l'existence d'effets non-locaux aux échelles micrométriques, faisant intervenir une taille caractéristique interprétée dans le cadre du modèle de fluidité. – Les ascensions capillaires de fluides complexes, aux échelles millimétriques. En revisitant l'expérience classique des ascensions capillaires dans le cas des fluides complexes, cette étude propose une extension de la loi de Jurin au cas des fluides à seuil. Il est montré que cette expérience simple permet de mesurer la tension de surface et quelques paramètres rhéologiques de fluides complexes tels que le seuil et l'exposant d'Herschel-Bulkley / Complex fluids such as gels, pastes or emulsions have a wide range of applications, both in everyday life and in the industry. Among them, Yield Stress Fluids (YSF) behave either as solids or as non-Newtonian fluids depending on the shear stress applied. These features are modeled by phenomenological laws ( such as the Herschel-Bulkley one ) although their origins are still poorly understood. In this thesis, we focus on the issue of small lengthscales where the structure and interfacial phenomena play predominant roles in the flows. This experimental work was essentially carried out on carbopol, a polymer microgel and a model YSF. The study mainly focuses on three points : – The rheological and structural characterization of the samples. The emphasis is put on the influence of the preparation protocol on the microgel properties. – The case of confined flows of complex fluids. This work highlights the existence of nonlocal effects at the micrometer scales, involving a characteristic length, interpreted in the frame of the fluidity model. – Capillary ascents of complex fluids, involving millimeter scales. This work suggests an extension of Jurin’s law to the case of YSFs. It is shown that this simple experiment allows to measure the surface tension and some rheological parameters of complex fluids such as the yield stress and the Herschel-Bulkley exponent

L’étude de la réponse membranaire suite au stress éthanolique chez Saccharomyces cerevisiae vise à comprendre les mécanismes impliqués dans la survie des eucaryotes aux concentrations en éthanol élevées. La membrane cellulaire, par sa position entre l’environnement intra et extracellulaire, est la première cible des perturbations éthanoliques. Les expérimentations effectuées dans cette étude visent à caractériser le maintien de l’intégrité fonctionnelle en relation avec la composition en stérols membranaires chez la levure S. cerevisiae soumise à différents types de perturbations éthanoliques (augmentation de la concentrations en éthanol dans le milieu de croissance, chocs éthanoliques d’amplitude croissante et suivi au cours du temps ; choc à 20% pendant 15 minutes puis suivi au cours du temps après retour dans un milieu sans éthanol (« pulse » 20% d’éthanol)). Les résultats obtenus démontrent l’importance de l’ergostérol dans le maintien de l’intégrité membranaire et supportent également l’hypothèse du rôle « vecteur » de l’éthanol vis à vis d’une oxydation, dont l’efficacité serait dépendante de la nature des stérols présents au niveau membranaire. Les premiers résultats analysant la cinétique de transcription de gènes impliqués dans la réponse au stress oxydatif suggèrent une formation plus importante de formes réactives de l’oxygène (ROS), induite par le choc éthanol chez un mutant Δerg6, affecté dans la voie de biosynthèse de l’ergostérol. / The study of membrane response induced by ethanol stress in Saccharomyces cerevisiae aims to understand mechanisms involved in the survival of eukaryotic cells submitted to high ethanol concentrations. The cell membrane by its position between the intra- and extracellular environment is the first target of ethanolic perturbations. Experiments performed in this study aimed to characterize the maintain of the functional integrity of the membrane in relation to the sterol composition in the yeast S. cerevisiae submitted to different types of ethanolic disturbances: increasing concentrations of ethanol in the growth medium; ethanolic shocks of increasing magnitude; shock 20% ethanol for 15 minutes and then return in a medium without ethanol ("pulse" 20% ethanol)). Our results demonstrate the importance of ergosterol in maintaining membrane integrity and also support the hypothesis of the vector role of ethanol in cell oxidation, whose effectiveness is dependent on the nature of sterols at the membrane level. In addition, our results analyzing the kinetics of transcription of genes involved in oxidative stress response suggest an increased formation of reactive oxygen species (ROS) induced by ethanol in the Δerg6 mutant, affected in the biosynthetic pathway of ergosterol.